RFR: 8290714: Make com.sun.jndi.dns.DnsClient virtual threads friendly

[Aleksei Efimov]

### The Proposed Change

The proposed change updates JNDI's `DnsClient` internal implementation to use `DatagramChannel` (DC) as a replacement for `DatagramSocket` (DS).
The main motivation behind this change is to make JNDI/DNS lookups friendly to virtual-thread environments and update its underlying implementation to use efficient `DatagramChannel` APIs.
 The list of proposed changes:
- Replace DS usage with DC. That includes the `DNSDatagramSocketFactory` class updates to return DC instead of DS. The factory class was renamed to `DNSDatagramChannelFactory` to reflect that.
- Change DNS query timeouts implementation - the current version introduces a nio channels selector to implement timeouts. One selector is created for each instance of `DnsClient`.
- Adjust query retries logic to the new implementation of timeouts.
- Modify the `Timeout` test to create a bound UDP socket to simulate an unresponsive DNS server. Before this change, the test was using the '10.0.0.0' network address that doesn't belong to any host. The proposed change with a bound unresponsive UDP socket is better for test stability on different platforms.


### Testing
`jdk-tier1` to `jdk-tier3 `tests are showing no failures related to the changes.
JNDI regression and JCK tests also didn't highlight any problems with the changes. 

Also, an app performing a DNS lookup from a virtual thread context executed with the following options `--enable-preview -Djdk.tracePinnedThreads=full` showed no pinned carrier threads. Before the proposed change the following pinned stack trace was observed:
```    java.base/sun.nio.ch.DatagramChannelImpl.park(DatagramChannelImpl.java:486)
    java.base/sun.nio.ch.DatagramChannelImpl.trustedBlockingReceive(DatagramChannelImpl.java:734)
    java.base/sun.nio.ch.DatagramChannelImpl.blockingReceive(DatagramChannelImpl.java:661)
    java.base/sun.nio.ch.DatagramSocketAdaptor.receive(DatagramSocketAdaptor.java:241) <== monitors:1
    java.base/java.net.DatagramSocket.receive(DatagramSocket.java:714)
    jdk.naming.dns/com.sun.jndi.dns.DnsClient.doUdpQuery(DnsClient.java:430) <== monitors:1
    jdk.naming.dns/com.sun.jndi.dns.DnsClient.query(DnsClient.java:216)
    jdk.naming.dns/com.sun.jndi.dns.Resolver.query(Resolver.java:81)
    jdk.naming.dns/com.sun.jndi.dns.DnsContext.c_lookup(DnsContext.java:290)
    java.naming/com.sun.jndi.toolkit.ctx.ComponentContext.p_lookup(ComponentContext.java:542)
    java.naming/com.sun.jndi.toolkit.ctx.PartialCompositeContext.lookup(PartialCompositeContext.java:177)
    java.naming/com.sun.jndi.toolkit.ctx.PartialCompositeContext.lookup(PartialCompositeContext.java:166)
    java.naming/javax.naming.InitialContext.lookup(InitialContext.java:409)

After proposed changes - pinned threads are not detectable.

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Commit messages:
 - 8290714: Make com.sun.jndi.dns.DnsClient virtual threads friendly

Changes: https://git.openjdk.org/jdk/pull/11007/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11007&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8290714
  Stats: 691 lines in 4 files changed: 362 ins; 305 del; 24 mod
  Patch: https://git.openjdk.org/jdk/pull/11007.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11007/head:pull/11007

PR: https://git.openjdk.org/jdk/pull/11007